FERGUSON, Mo. — Authorities were searching Sunday for two men suspected of shooting and wounding a police officer in Ferguson, the St. Louis suburb where there have been angry protests since a white officer fatally shot an unarmed 18-year-old black man last month.

Although there were two separate protests about the Aug. 9 shooting of Michael Brown happening around the time the officer was shot Saturday night, St. Louis County Police Chief Jon Belmar said he didn’t think they were related in any way to the attack on the officer.

The men fled when the officer approached them at around 9 p.m. because the community center they were standing outside of was closed, Belmar said at a news conference early Sunday. When the officer gave chase, one of the men turned and shot him in the arm, he said.

Belmar said the officer is expected to survive, but he didn’t identify the officer or give further details about his condition. He said the officer returned fire, but that police have no indication that either suspect was shot.

The shooting comes amid simmering tension between many community members and the police in Ferguson, where two-thirds of residents are black, but only three of the city’s 53 officers are African-American.

At around midnight Saturday, about two dozen officers stood near a group of about 100 protesters who mingled on a street corner, occasionally shouting, “No justice, no peace.”

Meanwhile, police had closed part of a nearby street as helicopters and officers from several law enforcement agencies canvassed the area in search of the two suspects.

Earlier Saturday, Brown’s parents told The Associated Press that they were unmoved by a videotaped apology released days earlier by Ferguson Police Chief Tom Jackson, whose attempt to march with protesters Thursday sparked a clash that led to several arrests.

When asked whether Jackson should be fired, Brown’s mother, Lesley McSpadden, said he should be. Brown’s father, Michael Brown Sr., said rather than an apology, they would like Darren Wilson, the officer who shot their son, to be arrested.

A county grand jury is weighing whether to indict Wilson in Brown’s shooting.

The Justice Department, which is investigating whether Brown’s civil rights were violated, is conducting a broader probe into the Ferguson police department. On Friday, it urged Jackson to ban his officers from wearing bracelets supporting Wilson while on duty and from covering up their name plates with black tape.

Ferguson residents complained about the bracelets, which are black with “I am Darren Wilson” in white lettering, at a meeting with federal officials this week.

Also early Sunday, not far from Ferguson, an off-duty St. Louis city police officer was injured on Interstate 70 when three suspects fired shots into his personal vehicle, a police spokeswoman said.

Schron Jackson said the officer, who has nearly 20 years of experience, was being treated at a hospital for a minor injury to his arm from broken glass. She said there is no reason to believe the two shootings were related.